Britain needs a dedicated security service to tackle internet hackers and terrorists, a Midland MP has warned.
Computer systems running essential services including the nation's nuclear power stations could be vulnerable to attack by groups such as al Qaida, said Mark Pritchard (Con The Wrekin).
Speaking in the Commons, he urged the Government to consider appointing a " cybersecurity tsar" to co-ordinate action against viruses and hacking.
The MP warned: "The rise of the professional hacker has serious implications for the UK, particularly in relation to national defence."
The number of attacks on computer networks recorded by the US had risen from 10,000 in 1999 to more than 400,000 in 2004, he said.
Recent high-profile examples include the Mydoom virus last year, which infected five million computers.
"Key national infrastructures, such as energy, transport, finance, telecoms and aviation, rely constantly on an exchange of information, primarily through computer networks.
"A penetration of any of those networks would be a serious threat to national security, not least when it comes to the potential to access Britain's 14 nuclear power stations."
Mr Pritchard added: "It is interesting that the imprisoned al Qaida members have admitted that their organisation has been attempting to - and no doubt is still attempting to - develop cyber threats to strike western Governments."
The US has an agency called the National Cyber Security Division to respond to cyberthreats, he said. "The rise in aggressive viruses and cyber security threats is a clear and present danger to Britain's national security."
He asked Ministers: "Would the Government consider forming a unified national cyber security agency, which would take a lead on their behalf and be a single point of cyber security information, guidance and advice for the nation?"
Trade Minister Barry Gardiner said the Government took the issue seriously.